The mass of an object is most often stated with the unit kilogram (kg). It refers to the amount of stuff in an object. The weight of an object refers to the force with which gravity pulls downward upon that stuff. The standard metric unit of weight is the Newton (N). These two quantities are related by the equation ...
Weight = mass • g
where g = gravitational field strength.
The value of g is location dependent. It varies ever so slightly across the surface of the Earth, being a slightly lower value at higher altitudes and nearer the equator. But overall, the value 9.8 N/kg is the generally accepted value for planet Earth.
In this question, the weight of the object is stated. It can be substituted into the above equation with the value of g in order to calculate the object's mass. You will have to do an additional algebra step to isolate the mass on the right side of the equation; you will have to divide through both sides of the equation by g.